Fix '_infer_str_format_call' crash when the string it analyses are uninferable (#2024)

Closes pylint-dev/pylint#8109

(cherry picked from commit ccbdd3c)

Author: Pierre-Sassoulas

ChangeLog

@@ -12,6 +12,9 @@ What's New in astroid 2.14.2?
 =============================
 Release date: TBA
 
+* '_infer_str_format_call' won't crash anymore when the string it analyses are uninferable.
+
+  Closes PyCQA/pylint#8109
 
 
 What's New in astroid 2.14.1?

astroid/brain/brain_builtin_inference.py

@@ -928,7 +928,9 @@ def _infer_str_format_call(
     """Return a Const node based on the template and passed arguments."""
     call = arguments.CallSite.from_call(node, context=context)
     if isinstance(node.func.expr, nodes.Name):
-        value: nodes.Const = helpers.safe_infer(node.func.expr)
+        value: nodes.Const | None = helpers.safe_infer(node.func.expr)
+        if value is None:
+            return iter([util.Uninferable])
     else:
         value = node.func.expr
 

tests/unittest_brain_builtin.py

@@ -9,7 +9,7 @@
 import pytest
 
 from astroid import nodes, objects, util
-from astroid.builder import _extract_single_node
+from astroid.builder import _extract_single_node, extract_node
 
 
 class BuiltinsTest(unittest.TestCase):
@@ -127,3 +127,22 @@ def test_string_format_with_specs(self) -> None:
         inferred = next(node.infer())
         assert isinstance(inferred, nodes.Const)
         assert inferred.value == "My name is Daniel, I'm 12.00"
+
+    def test_string_format_in_dataclass_pylint8109(self) -> None:
+        """https://github.com/PyCQA/pylint/issues/8109"""
+        function_def = extract_node(
+            """
+from dataclasses import dataclass
+
+@dataclass
+class Number:
+    amount: int | float
+    round: int = 2
+
+    def __str__(self): #@
+        number_format = "{:,.%sf}" % self.round
+        return number_format.format(self.amount).rstrip("0").rstrip(".")
+"""
+        )
+        inferit = function_def.infer_call_result(function_def, context=None)
+        assert [a.name for a in inferit] == [util.Uninferable]